A Study On Node Localization In Shallow Ocean Environment On TOA And DOA

Underwater target location technology is an important component of marine science research,and it has wide application prospect in underwater communication,sonar and national security.Target node localization based on TOA and DOA can achieve higher accuracy than RSS.Therefore,it will get a better effect while using these two technologies in underwater localization.In this paper,a joint TOA and direction-of-arrival DOA localization algorithm considering the inhomogeneous water medium in ocean multipath environment is addressed,and this algorithm has good theoretical significance and practical value of engineering.The main research of this paper is as follows:The shallow ocean environment is complex,and there are many uncertain factors affecting signal transmission.Therefore,the analysis of the signal parameters received at the reference node will increase the positioning error.In order to reduce the influence of this uncertain factor on localization,SVDD and AAKR are used to modify the parameters.Firstly,the sensor is placed in the target area,then the data that contains noise is received at different time,which is used as the training data of SVDD,the new data is classified by the classifier.According to the result,AAKR is used to obtain the similarity of the new data and database data so as to correct the data.The received data will be discriminated by SVDD again,if it is assigned to a negative class,then discard the data,otherwise the data added to the database as a standard data.The simulation results indicate that the data corrected are more accurate.To overcome the problem caused by the inhomogeneous water medium,we proposed the optimization algorithm of acoustic signal parameters,and a joint time-of-arrival(TOA)and direction-of-arrival(DOA)localization algorithm considering the inhomogeneous water medium in shallow ocean multipath environment is proposed.This algorithm can not only avoid the slanted path induced by the various sound speeds,but also reduce the influence of dynamic underwater network topology.Firstly,the virtual node(VN)of the anchor node was set up by the surface and the bottom of the sea to convert the non-line-of-sight(NLOS)problem into a line-of-sight(LOS)problem.Then,according to the known sound speed profile(SSP),the numerical path of signal was derived by using Fermat's Principle.Furthermore,due to the irregularity of sea surface and seabed,the signal is scattered at the reflection point.So the reflection point is regarded as a distributed source,and the central angle and the average arrival time is regarded as DOA and TOA,respectively.Finally,the location parameter of target was estimated by TOA and DOA.The simulation results indicate that the proposed method is superior to conventional straight line propagation model in location accuracy and robustness.